叶绿体是植物进行光合作用、脂类合成等重要物质代谢的场所，其发育是受核基因和叶绿体基因共同控制的复杂过程。对叶绿体发育过程的研究,将有助于提高绿色植物光能利用率和光合作用效率。叶绿体发育过程中的必需基因突变将导致叶绿体发育停滞、植株白化致死。而可稳定遗传的必需基因低表达突变株是研究叶绿体发育调控机制研究的理想材料。前期工作中，我们自主筛选得到了一个新的拟南芥花斑叶色突变体var6-1，该突变体的花斑叶色表型是由于PAC基因的低表达造成。PAC是一个功能未知的叶绿体发育的必需基因，其完全敲除突变体白化致死。本研究将以var6-1突变体为材料，进行叶绿体超微结构观察以及光合作用复合体积累的研究；研究 PAC基因的组织特异性；分析PAC是否形成蛋白复合体；筛选var6-1花斑表型的抑制突变体，并对感兴趣的抑制突变体进行基因克隆，来探索PAC基因在叶绿体发育过程中的生物学功能。

Chloroplasts are essential places for photosynthesis and the production of lipids and other metabolites. The process of chloroplast biogenesis is tightly controlled both by nuclear genome and plastid genome complicatedly. Studies on chloroplast biogenesis is important for enhancement of solar energy utilization and photosynthetic efficiency of vascular plants.Once an essential gene for chloroplast biogenesis has been interrupted, the development of chloroplast would be halted, which lead to albino lethal plants. Some available mutants, which have low level expression of essential genes, are ideal materials to study the regulation mechanism of chloroplast biogenesis. In previous work, we had identified one variegated leaf color mutant in Arabidopsis thaliana, designated as var6-1, which was caused by the low PAC gene expression. PAC is an essential gene for chloroplast biogenesis with unknown function, and the completely PAC knock-out mutant is albino lethal. This study will focuses on var6-1 mutants. By analysis of chloroplast ultra-structure, accumulation of photosynthetic complexes, tissue expression pattern of the PAC gene, and whether PAC paricipate in protein complexes, meanwhile with screening and map-based cloning for suppressors of the variegated phenotype of the var6-1 mutant, we are going to explore the biological functions of the PAC gene in chloroplast biogenesis.